Posts tagged ‘Argus II Retinal Prosthesis System’

Can you imagine what it must be like to go blind? Degenerative diseases of the eye such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP) can result in loss of vision and blindness.

Retinitis pigmentosa is an inherited genetic condition for which there is no cure. It results in the progressive loss of function of the retinal photoreceptors that convert light into electrical nerve impulses that travel down the optic nerve to the brain for processing into the images we see. As you reduce the ability to process light, so you start to lose your sight and can end up totally blind.

Several companies and research groups are now working on an artificial retinal prosthesis. The term “bionic eye” is often used to describe this research, which for many may conjure up the “$6 million dollar man“. This “hype” is, however, far from the reality of where the technology currently is at.

To date, only crude images can be detected. There is no dramatic restoration of sight or vision, instead the retinal prostheses currently only offer the ability to detect light and large shapes.

However, for those who are blind, being able to detect shapes and “see” a door, could help people enormously in their activities of daily living. In the same way that we have seen tremendous increase in the megapixels for digital cameras, so it is hoped that visual acuity will improve as the technology increases the number of pixels that can be processed.

There are several research groups and companies working on different types of electrodes and different implant locations in the retina, but in essence they have a common approach.

Most of the retinal prostheses in development use an external video camera to convert light to electrical signals that are transmitted wirelessly to a retinal implant (multielectrode array) that delivers a pattern of electrical signals to the retina. This electrical stimulation of the retinal cells results in signals being passed down the optic nerve to the brain where they are processed into visual images.

The Argus II Retinal Prosthesis System (Second Sight) is the most advanced in terms of commercial approval. It has obtained CE marking and is on the market in Europe where it sells for a price of $115,000 (Source: ExtremeTech).

On September 28, 2012, the FDA ophthalmics device panel will discuss the application by Second Sight to sell the Argus II system in the United States as a humanitarian use device.

The Argus II implant consists of a coil (for receiving and transmitting wireless data) fixed on the sclera (outside of eye) and a 60 electrode array positioned on the surface of the retina.

This animation from Second Sight explains how it operates:

Argus II Clinical Trial Results

The results of a multicenter trial with 30 patients at 10 centers were published earlier this year in Ophthalmology, a journal of the American Academy of Ophthalmology (AAO). Mark S. Humayun from the Doheny Eye Institute at University of Southern California and research colleagues reported that:

“Subjects performed statistically better with the system on versus off in the following tasks: object localization (96% of subjects), motion discrimination (57%), and discrimination of oriented gratings (23%). The best recorded visual acuity to date is 20/1260.”

In addition to finding the device to be reliable over the long-term, Humayun et al concluded that:

“The data in this report suggest that, on average, prosthesis subjects have improved visual acuity from light perception to at least hand movements, with some improving to at least counting fingers.”

“These visual acuity data and other performance results to date…demonstrate the ability of this retinal implant to provide meaningful visual perception and usefulness to subjects blind as a result of end-stage outer retinal degenerations.”

BSB: I saw in your Aug 30 media release that the implant was described as a “world first” by Dr Allen. Could you clarify in what way this is a “world first” when there are other retinal prosthetics on the market e.g. Argus II from Second Sight?

BVA: This is a world first implantation of a device in the suprachoroidal space at the back of the eye. Although there have been other groups working with patients around the world, this surgical position and procedure is unique to Bionic Vision Australia

BSB: How does the Australian Bionic Eye differ from the Second Sight product that is marketed in Europe?

BVA: There are a number of groups internationally working in the field of retinal implants – the fact that this research is ongoing means that the problem hasn’t yet been solved completely. Between all these groups there are a differences in technology being developed, materials used, surgical placement of the device, surgical technique and the way the electrodes or photodiodes are being stimulated (i.e. how the visual data is processed before it is sent to the implant).

At the end of the day, it’s all about ensuring the best outcome for patients. We are developing two prototypes, with different functional aims: the ‘wide-view’ device combines novel technologies with materials that have been successfully used in other clinical implants. This approach incorporates a microchip with 98 stimulating electrodes and aims to provide increased mobility for patients to help them move safely in their environment.

Our ‘high-acuity’ device incorporates a number of exciting and new technologies, such as diamond materials, to bring together a microchip and an implant with 1024 electrodes. The device aims to provide functional central vision to assist with tasks such as face recognition and reading large print. The early prototype that we implanted with our first three patients is a stepping stone towards further development for these two devices.

Bionic Vision Australia brings together researchers from many different fields, so we have a truly multidisciplinary team. This means the clinicians and surgeons are involved in the design and development process from the start. Further, a lot of our researchers were involved in the cochlear implant, or bionic ear development – they know what it takes to bring a competitive medical implant to the market.

BSB: I saw that your device was placed between the choroid and sclera, is that significant as opposed to being on the top of the retina? Could you provide further clarification on the significance of this and the surgical technique required for implantation?

BVA: Yes, this early prototype is implanted in the suprachoroidal space, between the choroid and the sclera. This is beneath the retina. There are a number of advantages in doing this, e.g. this position greatly enhances the mechanical stability of the implant and allows for a relatively straightforward surgery. The surgical procedure involves making an incision through the sclera and sliding the implant in place.

BSB: What are the next steps, is a larger clinical trial of your device already planned/underway – when will other patients receive implants?

BVA: We have implanted this early prototype in three patients and will continue to work with these patients over the next 18 months while we further develop our full prototype devices. The next step will be of course, a larger trial with our full devices in due course.

BSB: How might your device be potentially sold/commercialized or made available – is there a commercial partner associated with Bionic Vision Australia?

BVA: Bionic Vision Australia is an unincorporated joint venture between a number of research organisations in Australia. We are funded by the Australian Research Council. A commercialisation vehicle has been set up, Bionic Vision Technologies, to commercialise the technology. This company is solely owned by the member organisations that are involved in our research.

In addition to Second Sight and Bionic Vision Australia, there are several other companies and research groups with retinal prostheses in development.

It is an area where we are seeing innovation in action as teams of multi-disciplinary researchers strive to restore sight and improve the quality of life to people who have become blind.

However, given the high cost of R&D, and the fact that much of the research is government funded, I’m not sure of the commercial opportunity. It will be interesting to see how the market for retinal prostheses develops.

Challenges that have to be overcome

A number of challenges with retinal prostheses will have to be overcome. Some of these are discussed in a 2011 editorial by James Weiland, Alice Cho and Mark Humayun on “Retinal prostheses: Current Clinical Results and Future Needs” that was published in the AAO journal, “Ophthalmology.” I encourage anyone with an interest in this area to read this insightful review.

Some of the questions I took from this editorial were:

Why do some patients respond better than others with an implant?

Will retinal remodeling and ongoing degeneration limit the usefulness of implants?

What is the best surgical way to ensure optimal placement of the stimulating arrays to maximize visual acuity but avoid problems associated with fixation, and wound closure?

Could artificial vision be detrimental to other sensory inputs e.g. the ability of the visual cortex to process data from non-visual Braille reading?

Answers to these and other questions will come as clinical experience is gained and advances in technology improve the design and functionality. In my view this is innovation in action.

Second Sight presents updated results from the Argus II Retinal Prosthesis clinical trial, including sentence reading and color vision restoration for previously blind subjects. Two trial participants and independent investigators from the trial will be available for interviews.

Which brings me back to a Nature article published earlier this month that I have been meaning to write about showing, for the first time, the ability to generate a three-dimensional culture of neural retinal tissue from mouse embryonic stem (ES) cells. A word of warning, you may find the paper a little tough to follow unless you are a scientist in this field.

Eiraku and colleagues from Japan were able to culture retinal tissue similar to that seen in the human eye. Eye formation starts as an optical vesicle that then develops into a two-walled optic cup. As the authors note “optic cup development occurs in a complex environment affected by neighbouring tissues.”

What the authors showed in their research was the ability to culture retinal tissue containing ganglion cells, photoreceptors and bipolar cells. They conclude:

My take on this research is that it is an important milestone in regenerative medicine that could lead to the prospect of retinal transplants in the future. I look forward to learning more at ARVO about what the future may hold for retinal transplants derived from human stem cells.

Detecting a door or a window may not be a big deal for all of us with normal vision, but for those who lose their sight, e.g. through retinitis pigmentosa (RP), a new “artificial retina” now provides hope of a better quality of life.

The Argus™ II Retinal Prosthesis System from California based company Second Sight, has just received CE marking. This innovative device can now be sold and marketed within Europe, but it remains investigational in the United States. It is the first such device to be approved.

While this blog is mainly focused on the biotechnology industry, I’m very interested in innovation and bringing novel products to market. I also have a personal interest in the ophthalmology market. Earlier in my career, I spent three years at Alcon working with leading European ophthalmologists on intra-ocular lens clinical trials, including the IDE registration trial for AcrySof®.

In the same way that a cochlear implant does not restore hearing, the “artificial retina” or so-called “bionic eye” from Second Sight is not intended to restore vision, instead it artificially provides electrical signals that it is hoped the brain can learn to interpret as shapes.

The “artificial retina” has three parts, a small video camera worn in a pair of glasses that captures visual images. This transmits the electronic images to a video processing unit worn by the patient. Data is then transmitted wirelessly to an implant that is located on top of the retina.

The array of electrodes resting on the retina stimulates those rods and cones that remain functional to generate electrical impulses that are then transmitted down the optic nerve to the brain. Patients learn to interpret the patterns of light that are generated, and in the process gain some sense of visual perception that improves their daily life.

In an interview broadcast on French radio station, RTL one of the four French patients in the clinical trial, Thierry, talks about how this retinal stimulation device has improved his autonomy and quality of life.

When faced with blindness, any progress is noteworthy and it will be interesting to see the extent to which this technology can be further developed. I expect that more clinical trial data will be forthcoming at the annual meeting of ARVO (Association for Research in Vision and Ophthalmology) in May.

Update August 23, 2012: FDA Panel to review whether to recommend of approval of Argus II artificial retina in the United States

The FDA Ophthalmic Devices Panel will review on September 28, 2012 the Humanitarian Device Exemption (HDE) market approval application by Second Sight for its Argus II Retinal Prosthesis System with an indication for patients with severe to profound retinitis pigmentosa (RP) who have bare or no light perception in both eyes.

What is a Humanitarian Device Exemption?

“An HDE is similar in both form and content to a premarket approval (PMA) application, but is exempt from the effectiveness requirements of a PMA. An HDE application is not required to contain the results of scientifically valid clinical investigations demonstrating that the device is effective for its intended purpose. The application, however, must contain sufficient information for FDA to determine that the device does not pose an unreasonable or significant risk of illness or injury, and that the probable benefit to health outweighs the risk of injury or illness from its use, taking into account the probable risks and benefits of currently available devices or alternative forms of treatment.” U.S. Food & Drug Administration

Given the lower standard required for a HDE, and the fact that Second Sight obtained a CE mark in Europe, it would be hard to believe the FDA advisory panel will not recommend approval in a patient population that are effectively blind.

However, the FDA guidance also notes that an approval of an HDE, while allowing marketing of the device, does require it’s use to be at facilities where an institutional review board (IRB) has approved the use of the device. If approved for sale in the US, the market for Second Sight will be limited as a result to academic and hospital settings that have an IRB able to provide the necessary oversight and review.

“An approved HDE authorizes marketing of the HUD. However, an HUD may only be used in facilities that have established a local institutional review board (IRB) to supervise clinical testing of devices and after an IRB has approved the use of the device to treat or diagnose the specific disease. The labeling for an HUD must state that the device is an humanitarian use device and that, although the device is authorized by Federal Law, the effectiveness of the device for the specific indication has not been demonstrated.”

For those interested in more information, background material on the HDE application will be available on the FDA website no later than 2 days prior to the September 28 meeting of the Ophthalmic Devices Panel of the Medical Devices Advisory Committee.